1. Field of the Invention
Embodiments of invention relate generally to optical devices and, more specifically but not exclusively relate to limiting power in an optical beam.
2. Background Information
An optical power limiter is a device that can limit the intensity of light transmitted by the device to some value. Optical limiters can be useful for a number of purposes including protecting human eyes or sensors from high intensity light. Known optical power limiters include solid-state optical power limiters based on photoconductivity and the electro-optic effect has been observed in electro-optic crystals. Other known materials used for optical power limiting include molecular materials such as matallophthalocyanines and metallonaphthalocyanines, which exhibit relatively low linear absorption and high ratios of exited-state to ground-state absorption. Christiansen filters have also been utilized in optical power limiter applications to limit the maximum power transmitted by a device to some fixed value. Christiansen filters include for example small grains of crushed glass mixed with a liquid exhibiting a precise linear refractive index such that the glass grains disappear into the host liquid. An index mismatch between the liquid and glass components is induced by exposure to high intensity light, which therefore results in the optical power limiter behavior in the device. Use of the known optical power limiters such as those summarized above has been limited due to their complexity and the challenges involved with integrating and combining these technologies with other optical technologies into practical solutions.